Probes for optical measurements of tissue are being developed for a wide variety of applications and modalities, all focused on providing clinicians with details regarding the state of tissue to guide diagnosis or treatments. While the low penetration of light into biological tissue (on the order of 2 mm) restricts the use of optical techniques to surface or near surface measurements, the potential for optical probes to be miniaturized opens the possibility for probes to be combined with endoscopic or catheter-based techniques. This allows for optical measurements to be made in a wide variety of hollow organs (esophagus, colon, lung, etc.) and as a part of many minimally invasive surgical techniques. The optical modalities for which probes have been developed include broadband spectroscopy (ultraviolet, visible, near infrared, and short wave infrared), fluorescence, Raman spectroscopy, optical coherence tomography, photoacoustic tomography, coherence anti-Stokes Raman spectroscopy, confocal microscopy, among others.
Port-based or corridor surgery is a minimally invasive surgical technique where a port (generally a cylindrical plastic tube open on both ends) is introduced to access the surgical region of interest. Unlike other minimally invasive techniques, such as laparoscopic techniques, the port diameter is larger than the tool diameter, allowing bi-manual tool manipulation within the port. Hence, the tissue region of interest is accessible through the port. The presence of the tissue region of interest at a depth few centimeters below the skin surface and accessible through a narrow corridor allows for optical probe measurements to be made on regions of interest in close proximity to the tissue (contact probe within the port) and at a standoff distance from the tissue (stand-off probe position outside of the port).
While a wide variety of optical probes have been developed for numerous modalities, specific design aspects to enable and enhance the use of these probes within port-based surgery have not been developed. These include: the size of the probe, sterilization tolerance, signal enhancing mechanisms, integration with surgical tools, position and orientation tracking, and integration with other optical systems. At present the lack of these features hinders and restricts the use and utility of optical probes for port-based surgery.